Studies on asymmetric labeling of methyl groups are conducted, and the Biosynthetic Studies with Labeled Mevalonic Acid are continued. BIBLIOGRAPHIC REFERENCES: Biosynthesis of Sterols by a Yeast Homogenate. Incorporation of Mevalonic Acid into cholesta-5,7,24-trien-3 beta-o1 and 5 alpha-cholesta-7,24-dien-3 beta o1. Jacques P. Moreau, Peter J. Ramm, and Eliahu Caspi. European J. of Biochem., 56, 393 (1975). Synthesis and C-25 Chirality of 26-hydroxycholesterols. R.K. Varma, M. Koreeda, B. Yagen, K. Nakanishi and E. Caspi. J. Org. Chem. 40, 3680 (1975).